1. Field of the Invention
This invention relates to the manufacture of composite containers and primarily to the assembly of a hollow sleeve or label onto the body portion of a container for heat-shrinking in situ thereon. The sleeve may be formed immediately prior to its application to the container, or, alternately, the sleeve may be in preformed, flattened condition and taken to a position immediately below the container where it is opened and moved into telescopic alignment with the container held in upright relation. The final shrinking of the sleeve tightly around the body portion of the container is performed by subjecting the sleeve to controlled infra-red radiation supplied by electrical energy.
2. DESCRIPTION OF PRIOR ART
This invention comprises an improvement over the methods and apparatus disclosed in issued U.S. Pat. Nos. 3,767,496, issued Oct. 23, 1974; 3,802,942, issued Apr. 9, 1974; and 3,959,065, issued May 25, 1976, all of which are commonly owned by the same assignee as the present application. In each of these disclosures, a tubular sleeve is formed which is telescopically assembled onto the article from below by a push-up mechanism. None of these disclosures pertain to the thermal constriction of a thin, tubular sleeve of thermoplastic material which is telescoped upwardly over the upright container during their coincidental alignment and retention of the sleeve in place for its selective and controlled heating using infra-red radiation for thermoconstriction.
In many of the previously-disclosed methods and apparatus for making composite containers having an integral plastic sleeve or label thereon, a glass or plastic bottle is loaded onto a conveyor retained by its finish prior to mounting the plastic sleeve. The plastic sleeves are carried on an underlying turret to pass into alignment with the bottles and serially moved vertically upwardly into telescopic assembly over the body portion of the bottles. The sleeves are then carried on the bottles into a heating apparatus such as a gas-fired tunnel oven wherein appropriate physical conditions shrink the sleeves into close-fitting conforming arrangement surrounding the bottle body surfaces where assembled. The heating apparatus has commonly consisted of a gas-fired, hot air oven through which the bottles are passed, the oven temperatures ranging from about 170.degree. F. to 800.degree. F., depending upon the plastic material selected to form the sleeves.
U.S. Pat. No. 3,959,065, owned by the common assignee of this application, discloses method and apparatus which assure against dislocation of the sleeve on the bottle without external handling mechanisms being required to restrain the sleeve in place between its assembly point with the bottle and the shrinking oven. U.S. Pat. No. 4,048,281, also owned by the common assignee of this application, discloses a method of supporting the sleeve from underneath during heating for its shrinkage while both the bottle and sleeve are conveyed, a cooled holding bar being used.
Further, the cap sealing of bottles has been conventionally performed in recent years to provide for reasons of sanitation, pilfer-proofing, safety and appearance, the additional step of placing over and around the neck of the bottle, as well as preferably over at least part of its closure, a tubular sleeve of heat-contracting, synthetic resin material, severed to a prescribed length, and then shrinking the sleeve with hot air to conform to the bottle by thermal contraction. The synthetic resin tubing is usually pressed flat and delivered in rolls in many production processes, and since the tubing may or may not stay fully flattened, particularly where it is comprised of extremely flexible and resilient material, inefficiencies can and do result when the severed lengths of tubing are fitted onto the bottle necks.
It is also possible to apply the tubes around the bottle necks without preforming the material, as taught by U.S. Pat. No. 3,861,918 to Muto; however, such method normally requires the application of a bonding agent to the bottle neck for firm, permanent adherence of the sleeve. The method and apparatus disclosed by this patent are exceedingly more complex and prone to occasionally misapplying the tubular band or label. U.S. Pat. No. 2,852,899 to Murrell discloses a collar feeding mechanism which is designed to remove only the lowermost collar from a nested stack by frictional engagement with its inner surface. The collars are preformed and nested tightly into a stack from which they are deliverable onto the container necks.
Normally when heat-shrinkable thermoplastic sleeves are mounted on container such as glass or plastic bottles having generally cylindrical body portions, with the containers in upright relation for heat-shrinking a relatively large, tubular sleeve therearound, special care must be taken not to overheat the bottle during such heat shrinkage, especially in the case of plastic bottles, which can deform their sidewalls and alter their specific volume. It is to solve this problem, as well as to provide more efficient heat shrinkage that the present invention is primarily directed.